Apparatus for packaging a product with an extensible film

ABSTRACT

An apparatus for packaging a product with an extensible film, including a conveyor for conveying a product to the apparatus, an evacuating device for evacuating a product from the apparatus at the end of packaging, an unwinding device to unwind the extensible film from a reel mounted on the apparatus, a tensioning device for tensioning the extensible film, the unwinding device including a first gripping element and a second gripping element that are movable independently of one another in an unwinding direction for unwinding the extensible film from the reel.

The present invention relates to an apparatus for wrapping with an extensible film a product, in particular a food product placed on a paper or expanded polystyrene tray or on a tray made of another suitable material, or also without a tray, to make a light package that leaves the product in view, wrapping the product completely with a film that is transparent and extensible, for example of film of plastics.

From the prior art, apparatuses are known for automatically packaging a product in an extensible film that subject the film to pre-stretching, before wrapping the film around the product to be packaged, to maximise the extendibility features of the film material.

In known apparatuses, the film is folded in a preset direction to be, closed on the product. This does not enable the film to be adapted in all cases as well as possible to the shape of the product to be packaged and does not enable the quantity of film used in the packaging to be minimised.

The object of the present invention is to provide an apparatus for packaging a product with an extensible film that enables the film to be adapted as well as possible to the shape of the product to be packaged and the quantity of film used in packaging to be minimised.

The object of the present invention is achieved with an apparatus for packaging a product with an extensible film according to claim 1.

Owing to the apparatus according to the invention, it is possible to fold the film to close the film on the product, in two directions that are orthogonal to one another, it being possible to choose the folding direction on the basis of the shape of the product to be packaged, to optimise packaging of the product and minimise the quantity of film used.

Further, the apparatus according to the invention enables greater productivity to be obtained than with known prior-art apparatuses, packaging of loose products to be improved, i.e. products that do not rest on a tray.

Lastly, the apparatus according to the invention is easy to make and permits a high level of hygiene during the product packaging steps.

One manner of implementing the invention is illustrated, merely by way of non-limiting example, in the sixteen attached tables of drawings, in which:

FIG. 1 is a perspective view of an apparatus according to the invention;

FIG. 2 is also a perspective view of the apparatus according to the invention, observed from the side opposite FIG. 1;

FIG. 3 shows a detail of the apparatus according to the invention that illustrates the step of perforating the film intended for packaging a product;

FIG. 4 is a view like that of FIG. 1, which illustrates the positioning of the product to be packaged on a lifting device of the apparatus according to the invention, intended to lift the product, to bring the product into contact with the packaging film;

FIGS. 5 to 9 illustrate the steps of unwinding and tensioning the packaging film;

FIGS. 10 to 12 illustrate lifting of the product by the lifting device, to bring the product into contact with the packaging film;

FIGS. 13 to 16 illustrate wrapping of the product with the packaging film;

FIGS. 17 and 18 illustrate the exit of the product from the wrapping zone of the apparatus according to the invention at the end of packaging and welding of the flaps of the packaging film for final closing of the packaging of the product;

FIGS. 19, 20 and 21 illustrate three methods of packaging a product, made with the apparatus according to the invention.

In FIGS. 1 and 2 there is illustrated an apparatus 1 according to the invention for packaging a product P by means of an extensible film 3, for example a transparent film made of plastics, which is unwound from a reel 2.

The apparatus 1 comprises a conveying device 4 by means of which a product P to be packaged is inserted into the apparatus 1. The conveying device 4 can be associated with a weighing device 5 in which the product P is weighed. The conveying device 4 is further associated with measuring means (not shown) the purpose of which is to measure the width, the length, the maximum height, the average height and the shape of the product. These data are used to determine the movements of the various devices of the apparatus 1, which package the product P, and the quantity of film 3 to be used for packaging.

The conveying device 4 comprises a sliding surface 4 a on which a product P to be packaged is slid, possibly placed on a tray V, for example a paper or expanded polystyrene tray. The conveying device 4 comprises a first belt 6 wound on a first pair of pulleys 7 and a second belt 8 wound on a second pair of pulleys 9. The first belt 6 and the second belt 8 are parallel to one another and are driven by a first motor 10.

To the first belt 6 and to the second belt 8 two pushing elements 12 are fixed, each of which is suitable for pushing the product P to slide the product P on the sliding surface 4 a. The distance between the two pushing elements 12, measured along the first belt 6 and the second belt 8, and 8, is equal to half the length of the first belt 6 and of the second belt 8.

The conveying device 4 conveys the product P to be packaged to a lifting device 11 that lifts the product P to bring the product P into contact with the extensible film 3, as will be disclosed in greater detail below.

An end portion 62 of the sliding surface 4 a, opposite the weighing device 5, is provided with a plurality of protrusions 63 arranged in a slightly arched configuration, the purpose of which is to facilitate the transit of the product P from the conveying device 4 to the lifting device 11, avoiding possible blocking.

The lifting device 11 is driven by an actuator 13, which is suitable for moving the lifting device 11 in a direction that is substantially perpendicular to said sliding surface 4.

The extensible film 3, wound in the reel 2, is unwound from the latter by means of a first gripping element 14, which comprises a first fixed jaw 15 and a first movable jaw 16 by means of which the film 3 can be grasped. The first movable jaw 16 is movable between an open position, in which it is at a distance from the first fixed jaw 15, and a closed position, visible in FIG. 3, in which it is in contact with the first fixed jaw 15. The first fixed jaw 15 and the first movable jaw 16 have a width that is at least equal to the maximum width of the film 3 usable in the apparatus 1 according to the invention, so as to grasp the film over the entire width thereof when the first movable jaw 16 is in the closed position.

One end of the first movable jaw 16 is provided with a plurality of first teeth 24, arranged in a comb configuration.

The first movable jaw 16 is driven by a first cam element 17, driven by a first driving element 18, by a first arm 19. The first driving element 18 is controlled by at least one linear actuator, advantageously by a pair of linear actuators 20, 21.

The first gripping element 14 is slid, along linear guides 22, by first driving means 23 that comprises a linear actuator. The sliding of the first gripping element 14 unwinds the film 3 from the reel 2 in an unwinding direction S parallel to the linear guides 22.

Whilst the extensible film 3 is unwound from the reel 2, it is guided on a first guide roller 25, a second guide roller 26 and a third guide roller 27.

Downstream of the third guide roller 27, in the unwinding direction S of the extensible film 3 a perforating element 28 is arranged, consisting for example of a serrated blade, intended for making a series of holes in the extensible film 3, in a direction that is substantially perpendicular to the unwinding direction S. The perforating element 28 is driven by a second cam element 29 by a second arm 30 driven by the first driving element 18.

The first gripping element 14 is operationally associated with a second gripping element 31, having a structure that is similar to the structure of the first gripping element 14.

The second gripping element 31 in fact comprises a second fixed jaw 32 and a second movable jaw 33, with which the extensible film 3 can be grasped.

The second movable jaw 33 is movable between an open position, visible in FIG. 5, in which it is at a distance from the second fixed jaw 32, and a closed position, in which it is in contact with the second fixed jaw 33. The second fixed jaw 32 and the second movable jaw 33 have a width that is at least equal to the maximum width of the film 3 usable in the apparatus 1 according to the invention, so as to grasp the entire width of the film, when the second movable jaw 33 is in the closed position.

One end of the second movable jaw 33 is provided with a plurality of second teeth 34, arranged in a comb configuration.

The second teeth 34 are arranged staggered with respect to the first teeth 24 of the first movable jaw, so that the teeth of the two jaws can be inserted into one another, when the two jaws are brought into contact, as will be explained in greater detail below.

The second movable jaw 33 is driven by a third cam element 35, in turn driven by a second driving element 36, by means of a third arm 37. The second driving element 36 is controlled by at least one linear actuator 38, advantageously by a pair of linear actuators.

The second gripping element 31 is slid along the linear guides 22, by second driving means 39, which comprises a linear actuator.

The apparatus according to the invention further comprises a third gripping element 40 and a fourth gripping element 41 intended for performing transverse tensioning of the extensible film 3.

The third gripping element 40 and the fourth gripping element 41 are arranged so as to be able to grasp the opposite longitudinal edges 42 and 43 of the extensible film 3.

The third gripping element 40 comprises a third fixed jaw 44 and a third movable jaw 45, with which one of the longitudinal edges of the extensible film 3 can be grasped, for example the longitudinal edge 43. The third movable jaw comprises a plurality of jaw sections 45 a that are separate from one another (FIG. 7).

The jaw sections 45 a of the third movable jaw 45 are movable between an open position, visible in FIG. 8, in which they are at a distance from the third fixed jaw 44, and a closed position, in which they are in contact with the third fixed jaw 44.

The jaw sections 45 a of the third movable jaw 45 are driven by a third driving element 46.

The third driving element 46 is controlled by at least one linear actuator, advantageously by a pair of linear actuators 47 and 48. Preferably, all the jaw sections 45 a of the third movable jaw 45 are driven simultaneously. Nevertheless, it is possible to provide an independent drive for each jaw section 45 a.

The fourth gripping element 41 comprises a fourth fixed jaw 49 and a fourth movable jaw 50, with which the other longitudinal edge of the extensible film 3 can be grasped, for example the longitudinal edge 42, opposite the longitudinal edge 43.

Also the fourth movable jaw 50 comprises a plurality of jaw sections that are separate from one another, which are not visible in the figures.

The jaw sections of the fourth movable jaw 50 are movable between an open position, visible in FIG. 8, in which they are at a distance from the fourth fixed jaw 49, and a closed position, in which they are in contact with the third fourth fixed jaw 49.

The jaw sections of the fourth movable jaw 50 are driven by a fourth driving element 51. The fourth driving element 51 is controlled by at least one linear actuator, advantageously by a pair of linear actuators 52 and 53. Preferably, all the jaw sections of the fourth movable jaw 50 are driven simultaneously. Nevertheless, it is possible to provide an independent drive for each section of jaw.

The third gripping element 40 and the fourth gripping element 41 are slid along second linear guides 54 by respective third and fourth driving means 55 and 56. The third and fourth driving means 55 and 56 comprise respective linear actuators.

The second linear guides 54 are oriented in a direction that is substantially perpendicular to the direction of the first linear guides 22.

The lifting device 11 is movable in a direction that is perpendicular to the sliding surface 4 a between a lower position, visible, for example in FIGS. 1, 2, 4 and 6, in which it is substantially aligned on said sliding surface 4 a, and an upper position, in which the product P is packaged.

The motion of the lifting device 11 and that of the conveying device 4 are synchronised so that there is no downtime between the moment in which the lifting device 11 reaches the lower position and the moment in which a product P is pushed by one of the pushing elements 12, 12 a onto the lifting device 11.

The lifting device 11 is provided with a plurality of parallel grooves 57, oriented in a direction parallel to said unwinding direction S and sized in such a manner that the first teeth 24 of the first movable jaw 16 of the first gripping element 14 and the second teeth 34 of the second movable jaw 33 of the second gripping element 31 can be inserted into said grooves 57, as will be explained in greater detail below.

The apparatus 1 according to the invention further comprises a further pushing element 58, placed above the gripping elements 14, 31, 40 and 41, at a short distance therefrom.

The further pushing element 58 is driven by a pair of belts 59 driven by a second motor 60, so as to slide in a direction parallel to the second linear guides 54 to push the packaged product P onto an evacuating conveyor 61, by means of which the packaged product P is evacuated from the apparatus 1.

The evacuating conveyor 61 comprises a motor-driven band 62 made of a heat-resistant material, for example Teflon, which is heated by heating means, for example electrical resistances, for welding the film 3 wrapped around the product P, to complete packaging, as will be explained in greater detail below.

The operation of the apparatus 1 according to the invention is now disclosed.

A product P to be packaged, possibly placed on a tray V, is placed on the weighing device 5 associated with the conveying device 4 and is weighed.

After weighing has been performed, the conveying device 4 is driven so that one of the two pushing elements 12 pushes the product P along the conveying surface 4 a to the lifting device 11 which is moving to its lower position. In order to avoid downtime in the transit of the product P from the conveying device 4 to the lifting device 11, the conveying device 4 is synchronised with the lifting device 11, so that the product P is unloaded onto the lifting device 11 when the latter reaches its lower position, as shown in FIG. 4.

As soon as a product P has been moved from the weighing device 5 to the conveying surface 4 a, a new product can be placed on the weighing device 5. This is done with the object of minimising, or eliminating the operating downtime of the apparatus 1 according to the invention, to maximise the productivity thereof.

With the weighing device 5 and the conveying device 4 a plurality of measuring sensors is associated that, whilst the product P is weighed and moved along the conveying surface 4 a, detect the width, length, maximum height, average height and shape of the product. These data, combined with the dimensions of the reel 2, the features of the extensible film 3 and the type of the product (resistant product, light product, presence or absence of the tray V), are used to determine the movements of the elements of the apparatus 1 and the synchronisation thereof, for example the movements of the gripping elements 14, 31, 40 and 41, opening and closing of the movable jaws 16, 33, 45, 50, the movements of the lifting device 11, etc. The machine is thus completely automatic and is suitable both for all types of product P and of extensible film 3.

Whilst the product P is conveyed to the lifting device 11, the first movable jaw 16 of the first gripping element 14 is moved to a closed position and grasps a free end of the extensible film 3, whereas the first gripping element 14 starts to move in the unwinding direction S, unwinding the extensible film 3 from the reel 2.

The first gripping element 14 moves in the unwinding direction S until the first teeth 24 of the first movable jaw 16 are inserted into the second teeth 34 of the second movable jaw 33 of the second gripping element 31. The position of the second gripping element depends on the dimension of the product to be packaged, measured in the unwinding direction S.

At this point, the second movable jaw 33 closes, whilst the first movable jaw 16 opens, so that the extensible film 3 is retained by the second gripping element 31, which is moved in the unwinding direction S so as to unwind further the extensible film 3 from the reel 2, until a final position is reached that depends on the dimension of the product to be packaged, measured in the unwinding direction S. The quantity of extensible film 3 that is unwound from the reel 2 is defined by the movement of the second gripping element 31 in the unwinding direction S, i.e. by the final position of said second gripping element 31 at the end of said movement. Whilst the second gripping element 31 moves in the unwinding direction S, the first gripping element 14 moves back to a preset position that itself depends on the dimension of the product to be packaged, measured in the unwinding direction S.

Whilst the first gripping element retracts, the perforating element 28 can make a series of holes in the extensible film 3, in a direction that is substantially perpendicular to the unwinding direction S. This operation can, however, also be performed in a subsequent packaging step of the product P.

Whilst the first gripping element 14 moves to said preset position, the third gripping element 40 and the fourth gripping element 41 are advanced, by being slid along the second linear guides 54, until they reach a position in which they can grasp the side edges 42 and 43 of the extensible film 3. When the third gripping element 40 and the fourth gripping element 41 have reached the aforesaid position, the closure of the third movable jaw 45 and of the fourth movable jaw 50 is commanded so that the jaw sections of both jaws clamp the extensible film 3 against the third fixed jaw 44 and the fourth fixed jaw 49. It should be noted that not all the jaw sections of the third movable jaw 45 and of the fourth movable jaw 50 clamp the extensible film 3. In fact, the distance between the first gripping element 14 and the second gripping element 31, which depends on the dimensions of the product P in the unwinding direction S, can be less than the cross sections of the movable jaws 45 and 50. In this case, the outermost sections of the movable jaw interfere, by closing, with the first gripping element 14 and the second gripping element 31 without being able to clamp the film 3, which remains clamped between the sections of movable jaw of the third movable jaw 45 and of the fourth movable jaw 50 comprised in the space between the first gripping element 14 and the second gripping element 31.

The third gripping element 40 and the fourth gripping element 41, after clamping the longitudinal edges 42 and 43 of the extensible film 3 are retracted to tension the extensible film 3, whilst the product P is lifted by the lifting device 11 and comes into contact with the extensible film 3 which, whilst the lifting device continues to rise, is arranged on the upper part of the product P, as can be seen in FIG. 11.

During tensioning of the extensible film 3, the first gripping element 14 and the second gripping element 31 can move towards one another to avoid excessive tensions in the extensible film 3 and to limit the pressure of the film on the product P, in particular in the case of a soft product P.

When the lower part of the product P, or the bottom of the tray V, reaches the level of the first teeth 24 of the first gripping element 14 and of the second teeth 34 of the second gripping element 31, the first gripping element 14 and the second gripping element 31 are moved towards one another so that the first teeth 24 and the second teeth 34 are inserted into the grooves 57 of the lifting device 11 reaching below the product P, or the tray V, so as to support the product P (FIG. 12), thus enabling the lifting device 11 to return to the lower position to load a new product P.

Subsequently, the first gripping element 14 and the second gripping element 31 are advanced to place two flaps 65 of film under the product P, or the tray V. The first gripping element 14 and the second gripping element 1 are advanced until the first teeth 24 of the first gripping element 14 are inserted between the second teeth 34 of the second gripping element 31. In this manner the flaps 65 of film will be superimposed for a short portion D. The flaps 65 can be superimposed in a central position in relation to the product P, or to the tray V, as shown in FIG. 19, or in a decentred position, towards the end of the product P nearest the second gripping element 31, as illustrated in FIG. 21.

Superimposing the further flaps 65 in said decentred position enables the stroke of the second gripping element 31 to be reduced, thus advantageously limiting the dimensions of the apparatus in the unwinding direction S.

When the flaps 65 have been superimposed, the series of holes made in the extensible film 3 by the perforating element 28 is at the teeth 24 of the first gripping element 14. At this point, the second movable jaw 33 of the second gripping element 31 is opened, whilst the first movable jaw 16 of the first gripping element 14 is taken to the closed position to tear the extensible film 3, separating the portion of extensible film 3 wrapped around the product P from the rest of the film.

Moving the first gripping element 14 before closure of the first movable jaw 16 determines the quantity of extensible film 3 that is used in packaging the product P. Each flap 65 of film pressed between the bottom of the product P, or of the tray V, and the respective gripping element 14, 31, adheres to the product P, or to the tray V.

At this point, according to a first method for closing the extensible film 3 on the product P, the third gripping element 40 and the fourth gripping element 41 move underneath the product P, or the tray V, to each take a further flap 64 of film (FIG. 20) underneath the product P. Each further flap 64 of film pressed between the bottom of the product P, or of the tray V, and the respective gripping element 40, 41, adheres to the product P, or to the tray V. The further flaps 64 of film remain at a distance from one another other, the length of each further flap 64 of film being chosen in such a manner that the flap can remain adhering to the product P or to the tray V after being released by the third gripping element 40 and by the fourth gripping element 41.

After the further flaps 64 of film have been positioned underneath the product P, or underneath the tray V, the gripping elements 40, 41 are extracted from underneath the product P, or the tray V, releasing the flaps 64 of film, which remain adhering to the product P, or to the tray V.

As soon as the further flaps 64 of film have been positioned underneath the product P, or underneath the tray V, the gripping elements 14, 31 are extracted from underneath the product P, or the tray V, the flaps 65 of film remaining adhering to the product P, or to the tray V.

The first gripping element 14 and the second gripping element 31 then both move in the unwinding direction S to unwind a portion of film 3 intended for packaging a subsequent product P.

Simultaneously, by means of the second motor 60 and the pair of belts 59, the further pushing element 58 is driven that pushes the product P, with the possible tray V, on the motor-driven band 62 of the evacuating conveyor 61. The evacuating conveyor 61 conveys the packaged product P out of the apparatus 1 according to the invention and, simultaneously, through the effect of heating the motor-driven band 62, the further flaps 64 of film and the flaps 65 of film are welded together to form a closed casing of extensible film 3 around the product P, thus completing packaging thereof.

According to another method of closing the extensible film 3 on the product P, shown in FIG. 19, the first gripping element 14 and the second gripping element 31 take two flaps 66 of film underneath the product P, or the tray V, that have a sufficient length to ensure the adhesion thereof to the product P, or to the tray V, when they are released by the first gripping element 14 and by the second gripping element 31.

Subsequently, the third gripping element 40 and the fourth gripping element 41 take underneath the product P, or underneath the tray V, two further flaps 67 of film, superimposing the flaps for a portion D′, so as to complete wrapping of the product P. Upon completion of wrapping of the product P, the product P is pushed onto the evacuating conveyor 61, as explained previously.

The different methods disclosed for closing the extensible film make the apparatus 1 according to the invention very versatile and able to adapt easily to any shape of the product P. 

1-17. (canceled)
 18. An apparatus for packaging a product with an extensible film, comprising a conveyor for conveying a product in the apparatus, an evacuating device to evacuate the product from the apparatus at the end of packaging, an unwinding device to unwind the extensible film from a reel mounted on the apparatus, a tensioning device for tensioning said extensible film, a lifting device intended for receiving the product from said conveyor and lifting the product to bring the product into contact with said extensible film, said unwinding device comprising a first gripping element and a second gripping element that are movable independently of one another in an unwinding direction for unwinding the extensible film from the reel, said first gripping element comprising a first fixed jaw and a first movable jaw, one end of the first movable jaw being provided with a plurality of first teeth, arranged in a comb configuration, said second gripping element comprising a second fixed jaw and a second movable jaw, one end of the second movable jaw being provided with a plurality of second teeth, arranged in a comb configuration, wherein said lifting device is provided with a plurality of parallel grooves, oriented in a direction parallel to said unwinding direction and dimensioned so that the first teeth of the first movable jaw of said first gripping element and the second teeth of the second movable jaw of said second gripping element can be inserted into said grooves.
 19. The apparatus according to claim 18, wherein said tensioning device comprises a third gripping element and a fourth gripping element that are movable independently of one another in a direction that is perpendicular to said unwinding direction.
 20. The apparatus according to claim 18, wherein said second gripping element comprises a second fixed jaw and a second movable jaw, one end of the second movable jaw being provided with a plurality of second teeth, arranged in a comb configuration.
 21. The apparatus according to claim 20, wherein said first teeth and said second teeth are arranged staggered in relation to one another, so as to be able to be inserted into one another, when said first movable jaw and said second movable jaw are brought into contact with one another.
 22. The apparatus according to claim 19, wherein said third gripping element comprises a third fixed jaw and a third movable jaw, said third movable jaw comprising a plurality of sections that are separate from one another.
 23. The apparatus according to claim 19, wherein said fourth gripping element comprises a fourth fixed jaw and a fourth movable jaw, said fourth movable jaw comprising a plurality of sections that are separate from one another.
 24. The apparatus according to claim 18, wherein said conveyor comprises a sliding surface on which a product to be packaged can be slid and two pushing elements each of which is driven by a first belt and by a second belt moved by a first motor.
 25. The apparatus according to claim 18, wherein said conveyor comprises a weighing device.
 26. The apparatus according to claim 24, wherein an end portion of said sliding surface is provided with a plurality of protrusions arranged in a slightly arched configuration.
 27. The apparatus according to claim 18, wherein said evacuating device comprises a motor-driven band made of a heat-resistant material, said motor-driven band being heated by a heater.
 28. The apparatus according to claim 27, and further comprising a further pushing element intended for pushing a product packaged on said motor-driven band.
 29. The apparatus according to claim 18, wherein the movements of the second gripping element and of the first gripping element during packaging of said product determine the quantity of extensible film that is unwound from the reel for said packaging operation and the quantity of extensible film that is used in said packaging operation, respectively.
 30. A method for packaging a product with an extensible film, comprising: unwinding a portion of extensible film from a reel by a first gripping element and a second gripping element, said portion having a length depending on the dimensions of the product to be packaged; tensioning said extensible film by grasping opposite edges of said extensible film by a third gripping element and a fourth gripping element; placing said product, or a tray containing the product on a lifting device; bringing said product into contact with a lower face of said extensible film via a lifting device, raising the lifting device until the lower part of the product or of the tray reaches the level of said gripping elements, wherein it further comprises: bringing two flaps of film retained by the first gripping element and by the second gripping element under the lower part of the product, or of the tray, inserting the first gripping element and the second gripping element between said lifting device and the product or the tray so that they support the product or the tray, said flaps being pressed against the lower part of the product or of the tray to adhere to said lower part or to said tray; bringing two further flaps of film retained by the third gripping element and by the fourth gripping element under the lower part of the product, or of the tray, inserting the third gripping element and the fourth gripping element under the product or the tray said further flaps being pressed against the lower part of the product or of the tray to adhere to said lower part or to said tray.
 31. The method according to claim 30, and further comprising the step of superimposing on one another said flaps of film for a portion in a position that is central to the product, or to the tray.
 32. The method according to claim 30, and further comprising the step of superimposing on one another said flaps of film for a portion in a position that is off-center with respect to the product, or to the tray.
 33. The method according to claim 30, and further comprising the step of superimposing at least a portion of said further flaps on one another.
 34. The method according to claim 30, and further comprising comprising superimposing said further flaps on said flaps and welding together said flaps and said further flaps. 